Glucagon effect on glycogen content of chicken liver and muscles

The experiments were carried out on broiler chickens divided randomly into two groups differing in the feeding level and, consequently, in the rate of weight gain. Half the chickens in each group were given a single dose of glucagon 150 micrograms/kg, and the other half received a control solution of glycine buffer. The chickens were investigated 1--1.5 hour after feeding and after 18--20 hours of starvation using the technique of biopsy of the liver and the external pectoral muscle. In the biopsy specimens the glycogen level was determined immediately before glucagon administration and 30--60--90 minutes after the injection. It was found that glucagon injection caused either a rise or a fall in the glycogen level in the liver and that the trend of these changes depended on the feeding level of the chickens and on the duration of starvation of the birds before treatment. The glycogen level in the pectoral muscle of the chickens kept on the higher feeding level was observed to fall one hour after glucagon administration.     

The effect of propylthiouracil (PTU) on heat production in chickens maintained on different levels of nutrition

Using the method of forced feeding on higher and lower levels, two groups of chickens differring in growth rate were obtained. In the chickens of the two groups 72 measurements of heat production were made. Chickens of these groups were compared considering either the same age or similar body weight. It has been found that propythiouracil treatment (120 mg/kg duging 10 consecutive days) decreases heat production in the chickens of both groups. However, this effect was much more pronounced in the birds maintained on the higher level of nutrition and growing more rapidly than in those maintained on the lower level of nutrition and growing slowly.     

Modified metabolic responsiveness to glucagon in cold-acclimated and heat-acclimated rats

Calorigenic effect of glucagon on whole body oxygen consumption and interscapular brown adipose tissue (BAT) was investigated in unanesthetized and unrestrained warm controls (WC), cold-acclimated rats (CA) and heat-acclimated rats (HA). Glucagon produced significant elevation of oxygen consumption, body temperature and BAT temperature in all experimental groups. Such increased calorigenic responses to glucagon were significantly potentiated in CA and reduced in HA compared with those in WC. Thermogenic response of BAT to norepinephrine was also similar to that to glucagon; it was potentiated in CA, reduced in HA. These results indicate that glucagon would serve thermoregulatory nonshivering thermogenesis in temperature acclimation as calorigenic hormone, at least in part, through its action on BAT.     

Dietary thyrotropin-releasing hormone stimulates growth rate and increases the insulin: glucagon molar ratio of broiler chickens

The effects of thyroid manipulation on growth, feed efficiency, and plasma hormone levels were determined in rapidly growing chickens. Beginning at 3 weeks of age, eight broiler cockerels were provided with control feed (CF) or feed containing either 1 ppm of triiodothyronine (T3), 1 ppm of thyroxine (T4), 0.3% propylthiouracil (PTU), or 5 ppm of thyrotropin-releasing hormone (TRH) for 3 weeks. Blood samples were taken at 4, 5, and 6 weeks for determination of plasma levels of growth hormone, insulin-like growth factor, T3, T4, insulin, glucagon, glucose, and nonesterified fatty acids. Dietary TRH increased (P less than 0.05) the growth rate of chickens by 14% when compared with the CF group. Plasma growth hormone levels were reduced (P less than 0.05) 65% by dietary T3 and 33% by treatment with either T4 or TRH when compared with the CF group. Plasma insulin-like growth factor levels were 16% lower (P less than 0.05) in PTU-fed birds than the other treatment groups. Plasma T3 levels were elevated (P less than 0.05) 3-fold by dietary T3 and 38% by TRH whereas plasma T3 in the PTU group was 38% below the average of CF birds. Plasma T4 levels were increased (P less than 0.05) by 12-fold in T4-fed birds, decreased 48% in TRH-fed birds, and nondetectable in birds treated with either T3 or PTU. Compared with the other treatments, dietary PTU increased (P less than 0.01) plasma insulin levels 4.3-fold whereas TRH provided a 2.7-fold increase in plasma insulin. Plasma glucagon levels were 26% higher (P less than 0.05) in T3-fed birds than those fed either T4 or PTU. These observations indicate that thyroid activity plays an important role in regulating secretion of GH and the pancreatic hormones. Furthermore, our study demonstrates the potential use of TRH as an orally active growth promoter for poultry.     

An anti-insulin serum, but not a glucagon antagonist, alters glycemia in fed chickens.

Attempts at altering plasma glucose and, as a consequence, food intake were performed in fed broiler chickens by single i.v. injection of des-His1(Glu9) glucagon amide (a glucagon antagonist) or a non-stimulating anti-insulin serum. Plasma glucose level was not altered by des-His1(Glu9) glucagon amide but was rapidly and largely increased (for at least 2 h) by the injection of the insulin-immune serum. Hour and cumulative food intake were unaltered up to 10 h post injection. These results strongly suggest that in fed chickens, plasma glucose is mainly, if not exclusively, controlled by plasma insulin, and that the transient and heavy hyperglycemia evoked by inhibiting insulin action does not alter food intake.     

Anti-inflammatory and opioid-mediated effects of melatonin on experimental peritonitis in chickens

The immunomodulatory properties of melatonin (Mel) are generally recognized but the mechanisms of its action are not fully understood. In mammals, some of the immunomodulatory effects of Mel are mediated by opioids synthesized by immune cells under its influence. The present study was performed to examine whether Mel-induced opioids are involved in the immunomodulatory activity of Mel in chickens. Experimental peritonitis was evoked by a single ip injection of thioglycollate (TG), and half of the birds were pre-treated with Mel. Some of the Mel-treated birds were additionally pre-treated with naltrexone, an antagonist of opioid receptors. Control birds received an injection of saline, Mel or were untreated. At specific post-injection intervals chickens were sacrificed, the peritoneal cavity was flushed out and peritoneal leukocytes (PTLs) were counted. The activity of PTLs was measured in vitro by the level of reactive oxygen species (ROS). Splenocytes were isolated aseptically and mitogen-stimulated in vitro proliferation was assessed. In PTLs and splenocytes the expression of opioid (proopiomelanocortin and proenkephalin) genes was also examined. Mel exerted a bi-phasic effect on TG-induced peritonitis in chickens: initially it blocked the development of peritonitis, decreasing the number of PTLs and intracellular ROS level (anti-inflammatory action), and thereafter an increase in both PTL number and ROS level was observed (pro-inflammatory action). The pro-inflammatory effect occurred a few hours after the induction of expression of the proenkephalin gene in PTLs and both the proenkephalin and proopiomelanocortin genes in splenocytes. These effects were prevented by naltrexone, suggesting involvement of the opiatergic mechanism.     

Effects of genetic selection on growth rate and intestinal structure in the domestic fowl (Gallus domesticus)

1. Pieces of small intestine taken from chickens subjected previously to continuous selection, relaxed selection or no selection for rapid growth were used to estimate villus surface area and microvillus development to determine what effects genetic selection might have on factors controlling intestinal function. 2. Crypt size and the rates at which enterocytes migrated out of crypts were also measured, after injection of tritiated thymidine, to determine the time course of microvillus elongation. 3. Differences in growth rates measured between highly selected, relaxed selected or unselected birds were found to be correlated with parallel changes in villus surface area. Selection for growth did not change the density, dimensions or pattern of development of enterocyte microvilli. Microvilli did, however, produce a maximal 20-fold increase in villus surface area under all conditions. 4. Crypt size and enterocyte migration rates did not vary significantly between tissue taken from unselected and relaxed selected chickens. Tissue taken from highly selected birds had a crypt size and enterocyte migration rate 40% higher than values found for the other two groups of chickens. 5. The possibility that early genetic selection increased growth potential by uncoupling diet-induced changes on crypt hyperplasia from secondary effects on villus structure, and that later selection increased growth potential by increasing appetite, is discussed.     

Splenic leukocytes from chickens injected with Salmonella pullorum antigen stimulate production of corticosteroids by isolated adrenal cells

Corticosteroid levels in the blood serum of White Rock pullets were significantly increased within 1 hr after an iv injection of heat-killed Salmonella pullorum antigen (SP-Ag), and reached levels 7 to 10 times that of PBS-injected controls within 2 hr after SP-Ag injection. Incubations with isolated adrenal cells indicated that serum from SP-Ag-injected birds had the ability to stimulate the synthesis or release of corticosteroids twice that of serum PBS-injected birds. Stripping the serum from SP-Ag-injected birds with activated charcoal and precipitated silica (Quso G-32) removed the corticosteroids and the adrenal-stimulating ability. A 2-hr incubation of isolated adrenal cells with leukocytes from spleens removed from chickens 1 hr after injection with SP-Ag, using stripped serum as the medium, stimulated a two- to fivefold increase in corticosteroid as compared to splenic leukocytes from PBS-injected chickens incubated in the same medium. The results indicate that an "ACTH-like" substance was produced by the S. pullorum antigen-stimulated splenic leukocytes.     

Hypergammaglobulinemia in chickens congenitally infected with an avian leukosis virus.

Significantly elevated (2- to 5-fold higher than controls) serum levels of IgG were found in chickens congenitally infected with F42 strain of avian leukosis (ALV-F42) a subgroup A avian leukosis virus (ALV). A further increase in IgG levels in congenitally infected birds was found to be induced by injection of influenza virus in complete Freund's adjuvant(CFA). Serum immunoglobulin M (IgM) levels were not significantly elevated in ALV congenitally infected chickens except in those animals that had been injected with influenza virus in CFA. Hypergammaglobulinemia in ALV infected birds resulted only after congenital infection and not after infection of immunologically competent birds. Therefore this phenomenon appeared to have striking parallels with other persistent or chronic viral infections that have been previously described in mammals.     

The effects of bicuculline and muscimol on glutamate-induced feeding behavior in broiler cockerels

This study was designed to examine the effects of intracerebroventricular (ICV) injection of bicuculline (GABA_A receptor antagonist) and muscimol (GABA_A receptor agonist) on glutamate-induced eating response in 24-h food-deprived (FD24) broiler cockerels. At first, guide cannula was surgically implanted in the right lateral ventricle of chickens. In experiment 1, birds were ICV injected with different doses of glutamate. In experiment 2, birds were administered with effective dose of glutamate after bicuculline. In experiment 3, chickens received muscimol prior to the injection of glutamate, and cumulative food intake was determined at 3-h postinjection. The results of this study showed that glutamate decreases food consumption in FD24 broiler cockerels (P ≤ 0.05), and this reduction occurs in a dose-dependent manner. Moreover, the inhibitory effect of glutamate on food intake was significantly increased with bicuculline pretreatment, and this effect was attenuated with muscimol (P ≤ 0.05). These results suggest that there is an interaction between glutamatergic and GABAergic systems (through GABA_A receptor) on food intake in broiler cockerels.     

The effect of immunization against somatostatin on growth rates and growth hormone secretion in the chicken

The effect of both active passive immunization against somatostatin on growth rate and growth hormone levels was studied in chickens. Passive immunization against somatostatin by administration of antiserum had no effect on rate of growth of chickens and no persistent effect on circulating growth hormone (GH) levels. In acute experiments, administration of anti-somatostatin serum caused a marked elevation of GH levels in chickens at both 4 and 8 weeks of age, but the relative stimulation was greater in the older birds. Active immunization against somatostatin significantly stimulated growth rate in chickens, but was not shown to have a clear effect on circulating GH levels. These data suggest that somatostatin control over GH secretion may not be fully developed in the chicken at 4 weeks of age, but that immuno-neutralization of somatostatin can produce an increase rate of growth in chickens similar to that seen in mammals.     

The effects of glucagon and insulin on plasma thyroid hormone levels in fed and fasted domestic fowls

Glucagon injection (50 micrograms kg-1) produced a biphasic response in plasma thyroxine (T4) level in both fed and fasted chickens. An initial inhibition was followed by an increase to levels above control value. Glucagon reduced plasma triidothyronine (T3) possibly as a consequence of inhibition of peripheral monodeiodination. This inhibition persisted in fasted animals despite a glucagon induced hyperglycaemia. Insulin injection (4 IU kg-1) decreased plasma T4 concomitant with a profound hypoglycaemia. These effects were more pronounced in fasted birds. Insulin induced hypoglycaemia was associated with decreased plasma T3 probably as a consequence of reduced thyroidal T4 secretion and reduced peripheral monodeiodination. Glucagon and insulin may play direct or indirect roles in the regulation of thyroid hormone secretion and metabolism in the domestic fowl.     

The effects of DL-AP5 and glutamate on ghrelin-induced feeding behavior in 3-h food-deprived broiler cockerels

This study was designed to examine the effects of intracerebroventricular injection of DL-AP5 (N-methyl-D-aspartate (NMDA) receptor antagonist) and glutamate on ghrelin-induced feeding behavior in 3-h food-deprived (FD3) broiler cockerels. At first, guide cannula was surgically implanted in the right lateral ventricle of chickens. In experiment 1, birds were intracerebroventricularly injected with 0, 2.5, 5, and 10 nmol of DL-AP5. In experiment 2, chickens received 5 nmol DL-AP5 prior to the injection of 0.6 nmol ghrelin. In experiment 3, birds were administered with 0.6 nmol ghrelin after 300 nmol glutamate, and the cumulative feed intake was determined at 3-h postinjection. The results of this study showed that the intracerebroventricular injection of DL-AP5 increased food consumption in FD3 broiler cockerels (P ≤ 0.05), and this increase occurs in a dose-dependent manner. Moreover, the decreased food intake induced with the intracerebroventricular injection of ghrelin was additively enhanced by pretreatment with glutamate, and this effect was attenuated by DL-AP5 administration(P ≤ 0.05).These results suggest that there is an interaction between ghrelin and glutamatergic system (through NMDA receptor) on food intake in broiler cockerels.     

侧脑室注射胰高血糖素对兔血清高密度脂蛋白—胆固醇浓度的影响

我们最近曾报道,兔侧脑室内注射胰高血糖素有明显降低血浆自由脂肪酸的作用。本工作又观察了它对空腹血清高密度脂蛋白-胆固醇浓度的影响。结果如下: (1)能引起血清高密度脂蛋白-胆固醇(HDL-c)浓度的降低,且与注射剂量有依赖关系,注射后的75分钟降低最明显,以后逐渐恢复;(2)皮下注射阿托品(0.2mg/kg)或静脉注射酚妥拉明(5mg/kg)均不能消除其降低HDL-c的作用;(3)静脉注射心得安(5mg/kg)能阻断其降低血清HDL-c的作用。这似表明脑中胰高血糖素可能参与对血清HDL-c的调节,并可能是通过肾上腺素β-受体起作用的。     

Characteristics of specific adaptation to cold and their relation to aggressive behavior and the stress level in house mice

Change of calorigenic effect of noradrenaline after 5 week cold exposition (at 6-8 degrees C) as a criteria of specific adaptation was used. Individual differences of calorigenic reaction after cold exposition were negative correlation with blood corticosterone and positive correlation with aggressiveness in dyadic test.     

D-Trp8-D-Cys14-somatostatin--demonstration of its differential suppressive activity in juvenile diabetics.

In 8 insulin-dependent diabetics, the effect of D-Trp8-D-Cys14-somatostatin on blood glucose, growth hormone, and glucagon levels as well as on insulin requirements from an artificial endocrine pancreas was studied during a balanced meal. The somatostatin analogue was infused at a rate of 25 microgram/h preceeded by a bolus injection of 25 microgram 30 minutes before ingestion of the meal. At this dose the analogue had no effect on glucagon levels and insulin requirements from the artificial pancreas. On the other hand, there was a significant lowering effect on fasting blood glucose levels, possibly indicating a direct inhibition of hepatic glucose production. Furthermore, there might be a slight effect on growth hormone levels, as was demonstrated by a rebound increase after termination of analogue infusion.     

Dissociation of somatostatin effects. Peptides inhibiting the release of growth hormone but not glucagon or insulin in rats

Two analogs of somatostatin were tested for their effects on release of growth hormone, glucagon, and insulin after subcutaneous injection into rats. These peptides significantly suppressed pentobarbital-stimulated growth hormone release but showed no effect on arginine-stimulated glucagon or insulin release at dosages greater than 2 mg/kg. Somotostatin acts on all three secretions at dosages below 200 μg/kg.     

Comparison Between Effects of Standard Feed and Whole Wheat Supplemented Diet on Experimental Eimeria tenella and Eimeria maxima Infections in Broiler Chickens

The effects of experimental infections with Eimeria tenella (Experiment 1, n = 144) or E. maxima (Experiment 2, n = 216) in broiler chickens fed whole wheat, with or without access to grit, as compared to a standard pelleted feed were studied. Inclusion of whole wheat was gradually increased up to 30% at 3 weeks of age. Grit was given separately. The chickens were kept on litter in a parasite-free environment with free access to water and feed. At 3 weeks of age half the number of chickens were individually inoculated with 500 sporulated oocysts of E. tenella (Experiment 1) or 3 000 sporulated oocysts of Eimeria maxima (Experiment 2), and the remaining birds were kept separate as uninfected controls. Neither coccidiostats nor growth enhancers were used. Oocyst concentration was determined from each group separately. Intestinal lesions were scored on 6 birds per feed regime 7 d postinoculation, and on the remaining birds at slaughter. Diet had no significant effect on bird performance during infection. However, there was an indication that the E. maxima infection had more negative effect on weight gain in birds given standard feed than in those given whole wheat supplement, but the difference was not significant (p<0.09). The number of oocysts shed or mean intestinal lesion scores did not differ between diets in either experiment. In both experiments, the number of Clostridium perfringens was higher in the caeca of inoculated birds, but there were no differences between diets.     

Some biological activities of recombinant DNA-derived growth hormone on plasma metabolite concentrations in domestic fowl

The biological activity of recombinant-DNA-derived chicken growth hormone (rcGH) has been examined in young broiler cockerels, by determining its effects on plasma concentrations of glucose, free fatty acids and alpha-amino nitrogen. A single injection of rcGH increased plasma glucose, which remained high for several hours, whereas daily treatment with rcGH for 1 week had no effect on basal plasma glucose concentrations but blunted the glucose response to a further rcGH challenge. Plasma free fatty acids were also promptly increased following acute rcGH treatment, and chronic exposure to rcGH again attenuated this response. The effects of rcGH on plasma alpha-amino nitrogen were more variable. The stress of repeated blood sampling tended to reduce alpha-amino nitrogen, and after rcGH, an increase relative to vehicle-injected controls was seen in both acute and chronically-treated birds. These data suggest that rcGH has both hyperglycaemic and lipolytic activity in chickens, and may also increase amino acid availability.     

Tumor growth and antibodies after RSV-challenge in normal chickens and in chickens congenitally infected with avian leukosis virus.

Normal chickens and chickens congenitally infected with an avian leukosis virus (ALV) of antigenic subgroup A were challenged with strains of Rous sarcoma virus (RSV) of two different antigenic subgroups (B and C) and tumor induction and growth as well as humoral antibody to viral envelope antigen (VEA) and tumor-specific surface antigen (TSSA) were measured. There was no effect of congenital ALV infection on RSV tumor incidence or latent period but the growth rate and size of the tumors were much higher in congenitally infected birds as compared to controls. Whereas most tumors in the RSV-challenged normal birds regressed, tumors in ALV-infected birds grew progressively. There were no striking differences in the number of birds in either group in the incidence of anti-TSSA or anti-VEA antibodies nor did the presence of either type of antibody reflect the tumor status of the host.